#include <iostream>
#include <vector>
#include <string.h>

using namespace std;
vector<int> sub(vector<int> &A, vector<int> &B)
{
    vector<int> c;
    int i, t = 0;
    for(int i = 0; i < A.size(); i++)
    {
        t = A[i] - t;
        if(i < B.size()) t -= B[i];
        c.push_back((t+10) % 10);
        if(t < 0) t = 1;
        else t = 0;
    }
    while(c.size() > 1 && c.back() == 0) c.pop_back();

    return c;
}
bool cmp(vector<int> &A, vector<int> &B)
{
    if(A.size() != B.size()) return A.size() > B.size();


    for(int i = A.size() - 1; i >= 0; i--)
        if(A[i] != B[i])
            return A[i] > B[i];

    return true;
}
int main()
{
    string a, b;
    vector<int> A, B;

    cin >> a >> b;

    for(int i = a.size() - 1; i >= 0; i--) A.push_back(a[i] - '0');
    for(int i = b.size() - 1; i >= 0; i--) B.push_back(b[i] - '0');

    if(cmp(A, B))
    {
        auto c = sub(A, B);
        for(int i = c.size() - 1; i >= 0; i--) printf("%d", c[i]);
    }
    else
    {
        auto c = sub(B, A);
        printf("-");
        for(int i = c.size() - 1; i >= 0; i--) printf("%d", c[i]);
    }


    return 0;
}
